A pressure accumulation system for an internal combustion engine can prevent exhaust pressure from excessively increasing when pressurized gas is contained in a pressure accumulation container. A pressure accumulation system is applied for an internal combustion engine provided with an exhaust shut-off valve mounted in an exhaust path. The pressure accumulation system has a pressure accumulation tank into which gas can be introduced from that portion of an exhaust path. The pressure accumulation system also has a sensor for detecting the exhaust pressure, and an EGR valve is controlled based on the detection value from the exhaust gas sensor such that the pressure in that portion of the exhaust path which is on the upstream of the exhaust shut-off valve is limited below a predetermined exhaust gas upper limit value (Pmax) when gas is contained in the pressure accumulation tank.